A. Field of the Invention
The present invention mainly relates to a medical or industrial endoscope, or more particularly, to a device for preventing clouding of an observing window.
B. Description of the Prior Art
An endoscope is an optical instrument for observing and treating the body cavity, such as the stomach or intestines, by inserting a distal examining end of it to said body cavity. Flexible optic bundles are used for illuminating the object from said distal examining end and image-transmitting optic bundles are provided for optically coupling the observing window and an eyepiece of a grip end.
By the way, it often occurs that the observing window is covered by dew when the endoscope is inserted in the body cavity. This is because temperature of the observing window is lower than that of the body cavity at the beginning.
In the prior art, as detailed in the U.S. Pat. No. 4,076,018 to Heckele, a device is proposed for electrically warming the observing window. But, such a device is complicated and, moreover, it is undesirable to apply electric means to an instrument which is used in the body cavity.